A unit of electricity is one kilowatt-hour (kWh), and your bill counts units, not rupees, first. Two numbers give you the units: this month's meter reading minus last month's. From there, the slab rate turns units into money. A 1,000-watt appliance run for one hour uses one unit. This guide shows how to read units from the meter, how to estimate usage from appliance wattage, and how the slab rates build the final bill. You can also skip the maths with the free calculator linked below.
Units from the meter reading
Units consumed equal the current meter reading minus the previous reading. On a digital meter, read the figure marked kWh. On an older disc meter, read the dials left to right. Note the number on the same date each month for a clean comparison.
Multiply by the meter factor (MF) if it is not 1, though domestic meters almost always use an MF of 1. The result is the units that appear on your bill as units consumed.
Estimating units from appliances
You can estimate before the bill arrives using appliance wattage. Units used equal watts times hours, divided by 1,000. A 1.5-ton air conditioner draws around 1,500 watts, so eight hours a day uses about 12 units daily, or roughly 360 units a month from that one appliance.
Add the main loads: air conditioners, refrigerator, water pump, iron, and lighting. The sum is a fair monthly estimate, and it shows which appliance drives the bill.
Turning units into rupees
Slab pricing charges each band of units at its own rate. The first 100 units cost less than units above 300, and the rate rises with each band. Multiply the units in each band by that band's rate, add them up, and you have the energy charge.
Then add the extras: FPA, QTR, surcharges, electricity duty, GST and the PTV fee. These run from 18 to 28 percent on a typical domestic bill, so a rough shortcut is to add about a quarter to the energy charge.
Use the free calculator
The quickest route is the bill calculator on this site. Enter your monthly units, pick protected or unprotected, and it applies the slab rates and adds taxes for an instant estimate. It saves the band-by-band maths and lands close to a real domestic bill.
For the exact payable figure, check your real bill with your reference number. The estimate guides your budget; the bill carries the number you pay.
Tips & things to watch
- One unit is 1,000 watts run for one hour. A 1.5-ton AC uses roughly 1.5 units per hour.
- Read the meter on the same date monthly so your unit count matches the billing cycle.
- Add about a quarter to the energy charge to cover taxes and surcharges in a quick estimate.
Frequently asked questions
Subtract last month's reading from this month's. The result is your units consumed (kWh). Domestic meters use a factor of 1, so no extra multiplication is needed.
A 1.5-ton air conditioner draws around 1,500 watts, or about 1.5 units per hour. Eight hours a day works out near 360 units a month from that one unit.
One unit is one kilowatt-hour, or 1,000 watts running for one hour. A 100-watt fan for ten hours uses one unit.
No. The calculator gives a close estimate using indicative slab rates and taxes. Your real bill depends on the exact monthly FPA, QTR and taxes. Check the bill for the payable figure.